CVE-2021-1018 in Android
Summary
by MITRE • 12/15/2021
In adjustStreamVolume of AudioService.java, there is a possible way to determine whether an app is installed, without query permissions, due to side channel information disclosure. This could lead to local information disclosure with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-12Android ID: A-194110891
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Analysis
by VulDB Data Team • 12/22/2021
This vulnerability exists within the Android audio service implementation where the adjustStreamVolume method in AudioService.java contains a side channel information disclosure flaw. The issue allows malicious applications to determine whether other applications are installed on the device without requiring any specific query permissions or user interaction. This represents a significant privacy and security concern as it enables unauthorized enumeration of installed applications through indirect means. The vulnerability stems from how the system handles volume adjustments for different audio streams and exposes information about application presence through timing or resource allocation patterns that differ between scenarios where applications are installed versus those where they are not.
The technical flaw manifests when an application attempts to adjust audio stream volumes and the system's response varies based on whether target applications are installed. This differential behavior creates a side channel that can be exploited to infer application installation status. The vulnerability operates at the system level within the Android framework, specifically within the audio service component that manages audio routing and volume control. Attackers can leverage this information to build profiles of installed applications on target devices, potentially enabling more sophisticated attacks such as targeted malware delivery or reconnaissance activities. The flaw does not require any special privileges or user interaction, making it particularly dangerous as it can be exploited by any application running on the device.
The operational impact of this vulnerability extends beyond simple application enumeration, as it creates a persistent information leakage channel that can be used for various malicious purposes. An attacker could use this information to tailor phishing campaigns, deliver targeted malware, or conduct advanced reconnaissance for privilege escalation attempts. The vulnerability affects Android 12 systems and represents a failure in the principle of least privilege and information hiding within the Android security model. This type of information disclosure vulnerability aligns with CWE-200 (Information Exposure) and can be categorized under ATT&CK technique T1083 (File and Directory Discovery) and T1592 (Gather Victim Host Information) as it enables adversaries to collect information about the target system's application environment without explicit permission.
Mitigation strategies should focus on implementing proper access controls and ensuring that system-level operations do not leak information about installed applications. The Android security model needs to be strengthened to prevent side channel attacks by ensuring that volume adjustment operations provide consistent behavior regardless of application installation status. System updates should address the underlying implementation in AudioService.java to eliminate the information leakage channel. Additionally, developers should implement proper sandboxing and isolation mechanisms to prevent applications from exploiting such side channels. Organizations should monitor for exploitation attempts and consider implementing application whitelisting policies to limit the potential impact of such vulnerabilities. The fix should involve modifying the adjustStreamVolume method to ensure deterministic behavior that does not vary based on application presence, thereby eliminating the side channel that enables this information disclosure attack vector.